The use of biomarkers as measures of PTSD treatment efficacy and predictors of treatment outcomes: A systematic review.

The efficacy of posttraumatic stress disorder (PTSD) treatments might be hampered by individual differences. In order to maximize treatment efficacy in existing and newly developed interventions, controlling for individual variables is essential in treatment research. Given the marked physiological correlates of PTSD, biomarkers represent a promising solution. Throughout the PTSD literature, biomarkers have been used to assess treatment effects and predict treatment outcomes. However, the wide variety of biomarkers studied, along with several conflicting results, hinder researchers' abilities to comprehensively interpret the results reported. This systematic review of the literature aimed to identify and classify all biomarkers used to assess the efficacy of PTSD interventions and identify pre-treatment biomarkers able to predict treatment outcomes. Following PRISMA guidelines, we identified 70 studies that assessed biomarkers sensitivity to treatment effects and 25 that used biomarkers to predict treatment outcomes. Well-established treatments and newly developed protocols were included. The results were classified and interpreted by biomarker type. Indicators of neuroanatomical structures and functions were the most commonly studied biomarkers, followed by markers of cardiac activation and glucocorticoid analytes. Cardiac activation markers, and concretely heart rate reactivity to trauma cues, showed the most consistent findings, serving as a valuable method to assess treatment effects across different populations and treatment modalities. Other biomarkers showed promising trends both as predictors of treatment outcomes and measures of treatment efficacy, although essential methodological differences significantly impacted the comparison across studies.